INTRODUCTION The Cellular and Molecular Neuroscience (CMN) Core grew out of the former Pathology, Histology and Stereology (PHS) Core. The new Core reflects a reorganization, refocusing, and expansion of services. The reorganization mirrors a leadership change, with James Malter, MD, assuming the position of Core Director in 2003, along with a change and refocusing in the Core's activities from predominantly morphologic services (e.g., histopathology, slide preparation, and electron microscopy) to those more relevant to contemporary cellular and molecular neuroscience. The expansion of services reflects the addition of new state-of-the-art equipment (e.g., confocal and fluorescence microscopy, flow cytometry, phosphorimaging, and real time PCR) and specialized expertise (e.g., DMA gene arrays, proteomics, and viral vector production). Thus, the new CMN Core is not a cosmetic reshuffling but a true commitment to a host of new services, equipment, and support for the changing needs and composition of the MRDDRC Molecular and Genetic Sciences Group (MGSG)oftheMRDDRC.